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Microwave-to-optical phase synchronization techniques have attracted growing research interests in recent years. Here, we demonstrate tight, real-time phase synchronization of an optical frequency comb to a rubidium atomic clock. A detailed mathematical model of the phase locking system is developed to optimize its built-in parameters. Based on the model, we fabricate a phase locking circuit with high integration. Once synchronized, the fractional frequency instability of the repetition rate agrees to 6.35×10-12 at 1 s and the standard deviation is 1.5 mHz, which indicates the phase synchronization system can implement high-precision stabilization. This integrated stable laser comb should enable a wide range of applications beyond the laboratory. 相似文献
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An ultra-highly precise and long-term stable frequency transmission system over 120 km commercial fiber link has been proposed and experimentally demonstrated. This system is based on digital output compensation technique to suppress phase fluctuations during the frequency transmission process. A mode-locked erbium-doped fiber laser driven by a hydrogen maser serves as an optical transmitter. Moreover, a dense wavelength division multiplexing system is able to separate forward and backward signals with reflection effect excluded. The ultimate fractional frequency instabilities for the long-distance frequency distributed system are up to 3.14×10-15 at 1 s and 2.96×10-19 at 10 000 s, respectively. 相似文献
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基于无线传感器网络的教学实验平台设计 总被引:2,自引:0,他引:2
本文研究并开发了一种应用MSP430微控制器芯片和CC2420无线收发模块架构的无线传感器网络的教学实验平台,设计并实现了系统的总体架构、硬件电路、软件接口与数据汇聚模式,根据实践教学要求,设计了基于该平台系统的基本实验要求与操作步骤,给出了对不同层次实践教学的目标要求,最后给出教学实践效果的评价。 相似文献
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In this paper, we present an analytical solution of the interaction of the nanotube (NT) with a wedge disclination dipole in nanotube-based composites. The corresponding boundary value problem is solved exactly by using complex potential functions. The explicit expression of the force exerted on disclination dipole is given by using the generalized Peach- Koehler formula. As a numerical illustration, both the equilibrium position and the stability of the disclination dipole are evaluated for different material combinations, relative thickness of an NT, surface/interface effects, and the features of the disclination dipole. The results show that as the thickness of the NT layer increases, the NT has a relatively major role in the force acting on the disclination dipole in the NT-based composite. The cooperative effect of surface/interface stresses and the NT becomes considerable as the increase of NT layer thickness. The equilibrium position may occur, even more than one, due to the influences of the surface/interface stress and the NT thickening. The influences of the surface/interface stresses and the thickness of the NT layer on the force are greatly dependent on the disclination angle. 相似文献
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针对船舶自动识别系统(Automatic Identification System,AIS)中相邻多个小区的同频信号相互干扰、无法解调的问题,该文采用多天线接收混合信号,通过在FPGA上设计独立成分分析(Independent Component Analysis,ICA)算法来对混合信号进行实时盲分离.为满足实时性,文中用符号函数代替双曲正切函数对样点数据作非线性映射,简化迭代运算;并将样点数据分块存储,用于并行计算.同时实现了高精度特征分解(Eigen Value Decomposition,EVD),用于对混合数据进行白化.最后将设计的FPGA系统在Xilinx Isim中仿真,结果表明,主频20MHz时,系统在850μs内完成了从4路512点AIS混合信号中分离出了三路源信号.本文的设计也可应用于雷达、声纳等可能存在同频干扰的实时信号处理系统. 相似文献
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Time synchronization techniques, especially on the pulse per second (PPS) temporal basis, have attracted growing research interests in recent years. In this paper, we have proposed and experimentally demonstrated a high-precision two-way time transfer (TWTT) system to realize long-distance dissemination of 1 PPS signal generated by a hydrogen maser. A dense-wavelength-division-multiplexing (DWDM) system and bi-directional erbium-doped fiber amplifiers (Bi-EDFAs) have also been adopted to suppress the impact of Rayleigh backscattering and optimize the signal to noise ratio (SNR) as well. We have theoretically analyzed the systematic delay in detail. The ultimate root mean square (RMS) variation of time synchronization accuracy is sub-26 ps and the time deviation can be reduced to as low as 1.2 ps at 100 s and 0.253 ps at 12 000 s, respectively. 相似文献
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